Telescopes and Space Probes – Today’s Starry Messengers
Exciting news reached an Italian math professor in the summer of 1609 that a new invention was being shown off in the nearby town of Venice. A “spyglass”, two lenses in a tube that made far-away objects look near, fascinated Galileo, who quickly figured out how it worked and began making his own spyglass in his workshop. Galileo was as skilled as he was inquisitive, and although he was not the first to turn a spyglass to the sky, he was able to craft himself a better telescope (as we now call the spyglass) than any other.
During the rest of 1609 and into 1610, with ever more powerful telescopes, Galileo began making discoveries. The telescope allowed him to see the shadows cast by the mountains on the Moon, and he discovered that Jupiter had four satellites that orbited the planet like a mini solar system. Through his telescopes, the Milky Way turned from a wispy cloud into a vast swarm of countless stars; Venus became a planet which showed phases just like the Moon. Galileo published his discoveries in a book called Siderius Nuncius - "The Starry Messenger” which, despite its small size and informal tone, remains one of the most revolutionary books of science ever published. Galileo’s observations gave birth to modern astronomy and the first insights into the workings of a universe that continues to astound us.
In the 400 years since Galileo and his contemporaries used 16th century cutting-edge technology to explore the cosmos, astronomers are using 21st century cutting-edge technology to push our understanding of an increasingly strange and exciting universe. Just as in Galileo’s time, modern telescopes are a synthesis of the most advanced scientific thinking and engineering skill. NASA and its scientific and engineering partners have put the most advanced telescopes above the Earth’s atmosphere. In space, clear of the distortion and absorption of the air we breathe, the universe shines brightly from one end of the electromagnetic spectrum to the other.
Here are a few of NASA’s space telescopes – the modern Starry Messengers:
Hubble orbiting 350 miles above a cloudy ocean. Credit: NASAHubble Space Telescope
Placed into orbit to overcome the scourge of astronomers throughout time - the blurring of starlight by our atmosphere (not to mention cloudy nights!) The school bus sized HST has given us the most crystal-clear and beautiful images of the universe.
Artist’s rendering of the Chandra X-ray Observatory in orbit. Credit: NASA
Chandra X-ray Observatory
Chandra detects high energy light we call X-rays. X-ray telescopes reveal the most extreme events in our universe, like exploding stars and matter falling into black holes.
Artist’s rendering of the Spitzer Space Telescope in space. Credit: NASA
Spitzer Space Telescope
We can feel heat, but the Spitzer Space Telescope sees heat! Some objects in space are too cold to glow in visible light, but still radiate plenty of lower energy infrared light. Vast clouds of interstellar dust and gas, the raw materials for the next generation of stars, are dark and unseen by optical telescopes but shine brightly for Spitzer’s infrared detectors.
Artist’s rendering of the STEREO spacecraft orbiting the Sun. Credit: NASA
STEREO
A pair of orbiting telescopes stare at the Sun, giving us a 3-D view of the Sun’s surface. STEREO continues a long tradition of solar observations dating back to Galileo himself.
Artistic renderings of the Kepler and Fermi spacecraft in space. Credit: NASA
What of the Future?
Galileo’s legacy, and the vision of today’s astronomers, continues to push the boundaries of science and technology. The Kepler mission to find Earth-like planets around other stars is due for launch during the International Year of Astronomy, and the Fermi Gamma-ray Space Telescope, designed to detect the most extreme events in the universe, including the birth of black holes, will continue returning results in 2009.
Modern space technology has opened up a second front of exploration, allowing humans and robots to travel to some of the worlds that Galileo studied with his spyglass. The space probes and landers that explore our solar system at the beginning of the new millennium are part of a continuing quest to know our place in the cosmos, pioneered by Galileo and others four centuries ago. Here are a selection of the worlds studied by Galileo that have been visited by humans and robotic messengers from Earth.
Copernicus Crater looking across Mare Imbrium. Credit: NASA
The Moon
The Moon is the only place in the universe beyond Earth that humans have visited! Rock samples returned by Apollo astronauts showed that the Moon and the Earth were once one, separated at birth by a shattering collision. Modern exploration with spacecraft such as Lunar Reconnaissance Orbiter will pave the way for our return, this time as a stepping-stone to other worlds.
The surface of Venus mapped by Magellan. The image is colorized to bring out detail; the true color would be shades of grey. Credit: NASA
Venus
Galileo’s observations of Venus began a quest to find out what conditions were like on Earth’s twin world. The Magellan space probe mapped the surface of cloud-covered Venus from orbit, while the Venera landers discovered a planet that could not be more different from our own.
Jupiter and its Galilean moon Io, taken by the New Horizons spacecraft. Credit: NASA
Jupiter
Galileo discovered the four major moons of Jupiter, and it is fitting that a space probe called Galileo showed each moon to be a distinct and unique world. One of the Galilean moons, Europa, may even have liquid oceans below its icy surface. Scientists and engineers are already planning possible ways to explore this extraterrestrial sea.
Saturn’s rings and its moon Mimas, taken by the Cassini spacecraft. Credit: NASA
Saturn
The most distant known planet in Galileo’s time was an enigma. Saturn appeared to be three planets joined, or maybe one planet with handles! It was another fifty years before the handles were revealed as rings. Now the Cassini spacecraft is returning incredible images of the complex rings and unique moons as it continues its exploration of Saturn and its family.
